The Miradorn are a humanoid species from the Alpha Quadrant. This species has distinctive foreheads divided into two hemispheres (which seem to be bones). The species includes twins that together form two halves of one being, in something of a symbiotic relationship. If one twin dies, the other twin will anguish in the loss of "self". They are typically known for being a quarrelsome people.
In 2369, the Miradorn twins Ah-Kel and Ro-Kel raided a Vanoben transport with their Miradorn raider just two light years from Deep Space 9. Shortly thereafter, they appeared at Quark's attempting to sell the Ferengi the stolen item; a valuable, ornate egg metal sphere. In a botched robbery attempt masterminded by Quark, a Rakhari fugitive, named Croden, killed Ro-Kel. In retaliation, Ah-Kel vowed to avenge his brother's death, his only purpose now left in life, but died trying. (DS9: "Vortex")
The Miradorn makeup was one of makeup supervisor Michael Westmore's favorite designs from the first season of Deep Space Nine. In particular, Westmore liked the throat area. Originally, the throat had been designed with a loose flap of skin hanging down over the Adam's apple. However, costume designer Robert Blackman wanted to use a necklace as part of the Miradorn costume, but Westmore felt that to place a necklace over the flap of skin would render it useless and spoil the effect. As such, it was decided run the necklace under the flap of skin, and glue the skin down at the bottom, so it was no longer loose. Westmore has stated that he would like to explore this type of design again in the future. (Michael Westmore's Aliens: Season One, DS9 Season 1 DVD, special feature)